The present claimed invention relates to the field of flat panel or field emission displays. More particularly, the present claimed invention relates to the black matrix of a flat panel display screen structure.
Sub-pixel regions on the faceplate of a flat panel display are typically separated by an opaque mesh-like structure commonly referred to as a black matrix. By separating light emitting sub-pixel regions with a light-absorbing mask, the black matrix increases contrast ratio in bright ambient environments. It can also prevent electrons directed at one sub-pixel from being xe2x80x9cback-scatteredxe2x80x9d and striking another sub-pixel. In so doing, a conventional black matrix helps maintain a flat panel display with sharp resolution. In addition, the black matrix is also used as a base on which to locate support structures such as, for example, support walls.
In most prior art approaches, the support structures are connected to the black matrix using an adhesive. However, such prior art approaches have significant drawbacks associated therewith. As an example, in many prior art approaches it is necessary to precisely position the support structure with respect to the black matrix. More specifically, in some embodiments, complex alignment equipment must be used to ensure that the base of the support structure is being placed precisely onto a desired location on the black matrix. Such a problem is exacerbated when the support structure spans the entire length or width of the black matrix.
In addition to precisely placing the support structure at a desired location with respect to the black matrix, it is also necessary to keep the support structure at the precise location and with a desired orientation (e.g. not tilted or sloping) during subsequent processing steps. For example, if the base of the support structure is precisely positioned with respect to the black matrix, the top of the support structure must be kept from tilting until the top of the support structure is affixed to its designated anchor point. Such maintenance of the position of the support structure is critical to ensuring that the support structure functions properly. In one attempt to keep the support structure at a desired location, the black matrix has been used as a coarse positioning or xe2x80x9cbuttressingxe2x80x9d tool. Such an approach is described in commonly-owned U.S. Pat. No. 5,858,619 to Chang et al., entitled xe2x80x9cMulti-Level Conductive Matrix Formation Methodxe2x80x9d, issued Jan. 12, 1999. Although the teachings of the Chang et al. patent are beneficial, the invention of the Chang et al. patent does not provide the type of support necessary to ensure that the support structure is kept at the precise location and with a desired orientation (e.g. not tilted or sloping) during subsequent processing steps. The Chang et al. patent is incorporated herein as background material.
In other prior art attempts to solve some of the aforementioned problems, large amounts of adhesive are applied to, for example, the base of the support structure to securely affix the support structure to the top surface of the black matrix. However, such adhesives render adjusting or correcting of the position of the support structures difficult, tedious, or impractical. Also some prior art adhesives may deleteriously outgas contaminants into the evacuated active environment of the flat panel display device. As a result, certain types of adhesives may not be practical for use with flat panel display fabrication.
Additionally, although the aforementioned commonly-owned U.S. Pat. No. 5,858,619 to Chang et al., entitled xe2x80x9cMulti-Level Conductive Matrix Formation Methodxe2x80x9d, issued Jan. 12, 1999 describes a method for forming a matrix structure, the invention of the Chang et al. patent does not provide the type of support necessary to form contact portions for ensuring that the support structure is kept at the precise location and with a desired orientation (e.g. not tilted or sloping) during subsequent processing steps. As mentioned above, Chang et al. patent is incorporated herein as background material. That is, conventional matrix formation methods do not even remotely suggest or address formation of contact portions of a matrix structure.
Thus, a need exists for a black matrix structure formation method which eliminates the need for precise positioning of the support structure. A further need exists for a black matrix structure formation method which alleviates the problems associated with maintaining the support structure in a precise location and orientation during subsequent manufacturing steps. Still another need exists for black matrix structure formation method which eliminates the need for large quantities of tedious and polluting adhesives to hold the support structure in place.
Furthermore, in addition to the need for a black matrix formation method which meets the above-listed requirements, a need also exists for a black matrix formation method which produces a black matrix which is electrically robust. That is, a need also exists for a black matrix formation method which produces a black matrix structure which is adapted to retain a support structure within a flat panel display device, and which exhibits desired electrical characteristics even under electron bombardment during operation of the flat panel display device.
The present invention provides, in one embodiment, a black matrix structure which substantially reduces the need for precise positioning of the support structure by external means. The present embodiment further provides a black matrix structure which alleviates the problems associated with maintaining the support structure in a precise location and orientation during subsequent manufacturing steps. The present embodiment further provides a structure which eliminates the need for large quantities of tedious and polluting adhesives to hold the support structure in place.
Specifically, in one embodiment, the present invention provides a multilevel structure comprised, in part, of a first plurality of substantially parallel spaced apart ridges (hereinafter also referred to as first plurality of parallel ridges). That is, the first ridges are spaced apart in a substantially parallel orientation. The multi-level matrix structure further includes a second plurality of substantially parallel spaced apart ridges (hereinafter also referred to as a second plurality of parallel ridges). That is, the second ridges are spaced apart in a substantially parallel orientation. The second parallel ridges are oriented substantially orthogonally with respect to the first parallel ridges. In this embodiment, the second parallel ridges have a height which is greater than the height of the first parallel ridges. Furthermore, in this embodiment, the second plurality of parallel spaced apart ridges include contact portions for retaining a support structure at a desired location within a flat panel display device. Hence, when a support structure is inserted between at least two of the contact portions of the multi-level support structure, the support structure is retained in place, at a desired location within the flat panel display device, by the contact portions.
The present invention provides, in one embodiment, a black matrix structure formation method which substantially reduces the need for precise positioning of the support structure. The present embodiment further provides a black matrix structure formation method which alleviates the problems associated with maintaining the support structure in a precise location and orientation during subsequent manufacturing steps. The present invention also provides, in one embodiment, black matrix structure formation method which substantially reduces the need for large quantities of tedious and polluting adhesives to hold the support structure in place.
Specifically, the present invention provides a method for forming a contact portion of a matrix structure wherein the contact portion is adapted to locate and retain a support structure within a flat panel display device. In this embodiment, the present invention disposes a polyimide precursor material up on a substrate. The substrate is a substrate to which cured polyimide material is strongly adherent. Next, the present embodiment subjects the polyimide precursor material to a thermal imidization process such that an extending region of the cured polyimide material is formed proximate to the substrate. Upon the completion of the thermal imidization process, the present embodiment selectively etches the substrate to undercut the substrate from beneath the extending region of the cured polyimide material. As a result, the extending region of the cured polyimide material comprises the contact portion of the matrix structure. In this embodiment, the extending region of the cured polyimide material is adapted to retain a support structure within the flat panel display device.
In another embodiment, the present invention provides a method for forming a multi-layer heterostructure contact portion of a matrix structure wherein the multi-layer heterostructure contact portion is adapted to retain a support structure within a flat panel display device. More specifically, in this embodiment, the present invention disposes a polyimide precursor material upon a first surface of a first substrate. The first surface of the first substrate is comprised of a material to which cured polyimide material is strongly adherent. Next, the present embodiment subjects the polyimide precursor material to a thermal imidization process such that an extending region of the cured polyimide material is formed proximate to the first surface of the first substrate and such that a retracted region of the cured polyimide material is formed distant from the first surface of the first substrate. In the present embodiment, the first surface of the first substrate comprises a first part of the multi-layer heterostructure contact portion of the matrix structure. The first surface of the first substrate is adapted to retain a support structure within the flat panel display device.
In yet another embodiment, the multi-layer heterostructure contact portion is formed using a plurality of substrates which have cured polyimide disposed therebetween. The multi-layer heterostructure contact portion is fabricated in a manner similar to that described in the previously described embodiment. In the present embodiment, the plurality of substrates comprise the multi-layer heterostructure contact portion of the matrix structure, and are adapted to retain a support structure within the flat panel display device.
In another embodiment, the present invention provides a black matrix formation method which meets the above-listed requirements, and which produces a black matrix which is electrically robust. That is, another embodiment of the present invention provides a black matrix formation method which produces a black matrix structure which is adapted to retain a support structure within a flat panel display device, and which exhibits desired electrical characteristics even under electron bombardment during operation of the flat panel display device.
Specifically, in the present embodiment, the present invention forms a first plurality of substantially parallel spaced apart conductive ridges above a surface to be used within a flat panel display device. The present embodiment then forms a second parallel ridges above the surface to be used within a flat panel display device. The second parallel ridges are oriented substantially orthogonally with respect to the first plurality of substantially parallel spaced apart conductive ridges. Additionally, in this embodiment, the second parallel ridges having a height which is greater than the height of the first plurality of substantially parallel spaced apart conductive ridges. Also, the second plurality of parallel spaced apart ridges including contact portions for retaining a support structure at a desired location within a flat panel display device. Next, the present embodiment applies a dielectric material to the first plurality of substantially parallel spaced apart conductive ridges. The present embodiment then removes a portion of the dielectric material from the first plurality of substantially parallel spaced apart conductive ridges such that an exposed region of the first plurality of substantially parallel spaced apart conductive ridges is generated. Then, the present embodiment deposits a layer of conductive material over the first plurality of substantially parallel spaced apart conductive ridges such that the conductive material is electrically coupled to the exposed region of the first plurality of substantially parallel spaced apart conductive ridges.
These and other objects and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments which are illustrated in the various drawing figures.